Whilst there is a trend for increasingly compact turbines, there are, on the other hand, turbines being produced that are ever larger. The large horizontal axis wind turbines (HAWT) are known from their presence on wind farms. Their star-shaped rotor is usually fitted with three blades and these rotate in front of a mast or tower around a horizontal axis. Vertical axis wind turbines (VAWT) are used completely differently. As they usually rotate independently of the wind direction they do not need a yaw drive system, however, they have a lower level of performance. Above all, they supply electricity for personal use.

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The Turbina company focuses on this aspect with its small wind turbines. Turbina’s technology has been developing since 2006, and as of 2009, the company’s installations have been used on all five continents and in all types of weather conditions. Soon 500 watt turbines are to be produced in addition to the 4 kilowatt and 1 kilowatt turbines. The development phase is due to be completed by the end of 2014. The turbines are intended to supply cabins, mobile homes and ships, extend wireless networks and to produce electricity worldwide in areas that are not yet developed.

Turbina is managed by Aleksandar Vucak, Joachim Hausser and Marcus Kuchler. The design and technical basis are developed by Kuchler’s agency, Marwin. Turbina’s engineers then implement the technical and electronic functions. We asked Marcus Kuchler a few questions about VAWTs.

According to which principle do your products function? They are not only a lot smaller than the turbines we know from wind farms but they are also a different shape.

Turbina works on the rotor/stator principle. Vertical, fixed vanes always direct the wind from any direction at the optimum angle to the moving rotor blades that rotate around a vertical axis. This rotor moves as a pure ram pressure wing from 1.5 m/s – that is slower than walking pace – and produces a nominal power of between 12 and 14 m/s wind speed. The aerodynamically closed structure also operates a speed limitation in the event of storms so that it does not need a braking system.

Which materials are used?

The 1 kilowatt system in the latest generation for example is made of up to 85 per cent aluminium and is equipped to withstand extreme weather conditions like salt, sand, hail and ice. The remainder is made of aluminium die casting or high-quality steel.

What is your ultimate goal?

Above all, we want to develop small, unobtrusive wind systems that work quietly and safely so that wind power will also be able to be used in populated areas without having to make huge investments.

Why are such small systems for self-supply needed in populated areas? A small cabin in the forest is not on the electricity grid but a family house in a residential area is surely well supplied with energy, wouldn’t you say?

Owner-occupiers would like to have security and independence “within their own four walls”. This is a fact in the urban setting but dramatically rising electricity prices and a very opaque supply policy create the urge to loosen our dependence on external electricity suppliers – or even cut ties completely. For decades, there has been a boom in constructing low-energy houses and this can be traced back to this trend. Our systems have an operating noise level of 32 dB/a and that means they are quieter than a refrigerator. And they turn at 1.5 m/s wind speed. Traditional wind power systems require 3 to 6 m/s to turn.

How is this achieved?

The principle of ram pressure wings allows a low engine speed, which in turn, does not produce any noise. The large area of the ram pressure wing takes more wind than a narrow propeller blade and therefore moves much earlier when the wind increases.

You say that “neither birds nor bats will be threatened or endangered” by your systems.

Yes, the closed construction gives animals the impression of a solid body that they can fly past and not through. The rotor area of a conventional wind turbine with a horizontal axis only becomes a disc-shaped wind contact area as a result of the rapid rotation of the rotor blades. This does not happen in nature and so animals, above all, birds fly through this apparently free area and are caught by the rotor blades.